QLC Goes To 8TB: Samsung 870 QVO and Sabrent Rocket Q 8TB SSDs Reviewed
by Billy Tallis on December 4, 2020 8:00 AM ESTMixed Random Performance
Our test of mixed random reads and writes covers mixes varying from pure reads to pure writes at 10% increments. Each mix is tested for up to 1 minute or 32GB of data transferred. The test is conducted with a queue depth of 4, and is limited to a 64GB span of the drive. In between each mix, the drive is given idle time of up to one minute so that the overall duty cycle is 50%.
The 8TB Sabrent Rocket Q's performance on the mixed random IO test is much better than any of the other low-end NVMe drives; the DRAMless TLC drives are the slowest in this bunch, and the Intel 660p with its four-channel controller cannot keep up with the Rocket Q's 8-channel Phison E12. The 8TB Samsung 870 QVO is slower than most of the other SATA drives in this bunch, but still has a clear advantage over the 1TB model.
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| Power Efficiency in MB/s/W | Average Power in W | ||||||||
The high-end consumer NVMe drives and the Samsung 860 EVO TLC SATA drive top the power efficiency chart for the mixed random IO test. The Sabrent Rocket Q's efficiency is a significant step down from there, but still a bit better than any of the other low-end drives. The 8TB 870 QVO's efficiency score is worse than the 4TB model's, but clearly better than the 1TB model or either of the DRAMless TLC NVMe drives.
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Both of the 8TB QLC drives show fairly typical performance curves for the mixed random IO test: little or no performance drop when writes are first added to the mix, and then increasing performance that accelerates toward the end of the test as write caching becomes more effective. The 8TB 870 QVO doesn't show the signs of a filled SLC cache that we see from the 1TB model, and neither 8TB QLC drive shows the nearly-flat performance exhibited by the two DRAMless TLC drives.
Mixed Sequential Performance
Our test of mixed sequential reads and writes differs from the mixed random I/O test by performing 128kB sequential accesses rather than 4kB accesses at random locations, and the sequential test is conducted at queue depth 1. The range of mixes tested is the same, and the timing and limits on data transfers are also the same as above.
The Sabrent Rocket Q's performance on the mixed sequential IO test is competitive with the high-end consumer TLC drives, and far better than the other low-end NVMe options. The 8TB Samsung 870 QVO has distinctly lower performance than the smaller capacities, but isn't quite the worst overall performer.
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| Power Efficiency in MB/s/W | Average Power in W | ||||||||
The good performance of the Rocket Q on the mixed sequential IO test comes at the cost of worse power efficiency than the DRAMless TLC competition, but its efficiency scores are still decent. The 8TB 870 QVO's efficiency scores are worse than any of the other consumer SSDs in this bunch.
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As with several other synthetic tests in our suite, the mixed sequential IO test has the Sabrent Rocket Q showing rather variable performance, though fortunately without any severe drops. It performs a bit better during the more write-heavy half of the test.
The Samsung 870 QVO shows relatively flat and consistent performance throughout this test, but as is common for Samsung drives there's a bit of a decreasing performance trend during the read-heavy half of the test.
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shelbystripes - Thursday, December 10, 2020 - link
Dude, you don't seem to understand how "consumerist capitalism" DOES work. QLC will still be more than good enough for most consumers, or at least, that's what manufacturers are banking on. They still need to sell the hardware, and they're competing in a world where MLC and TLC SSDs still widely exist.The only way to get there will be lower cost... and there will be plenty of consumers who respond to high-capacity QLC SSDs at lower costs than "scale" alone can achieve for MLC or TLC drives, and who won't care about the drop in MTBF because QLC SSDs still have more total writes than they'll ever need. QLC SSDs aren't going to be for everyone, but if TLC (even 3D TLC) is such cheap technology that "scale" is all you need to hit 8TB SSDs with it, why isn't anyone making sub-$1K 8TB 3D TLC drives and competing with these? Shouldn't they be?
You just don't know what you're talking about, yet you have the arrogance of someone prepared to speak for everybody uniformly.
boozed - Saturday, December 5, 2020 - link
The Sabrent appears to perform quite well in real world tests, regardless of its synthetic/theoretical performance. Is this a bad thing?Hixbot - Saturday, December 5, 2020 - link
MLC/TLC is still available at extra cost. Meanwhile QLC is pushing HDDs out of the market.Oxford Guy - Sunday, December 6, 2020 - link
"MLC/TLC is still available at extra cost."Economy of scale. QLC is an attack on TLC and MLC.
Oxford Guy - Sunday, December 6, 2020 - link
Also the article says:"QLC NAND offers just a 33% increase in theoretical storage density, but in practice most QLC NAND is manufactured as 1024Gbit dies while TLC NAND is manufactured as 256Gbit and 512Gbit dies."
Which means manufacturers are trying to kneecap TLC to push QLC.
Spunjji - Monday, December 7, 2020 - link
Or it means that manufacturing TLC at those capacities per die would result in a bloated die size with decreased yields, increased costs, and too-few dies per drive to reach competitive speeds at the most common capacities.The problem with having a conclusion and looking for evidence to support it is that you can come up with all sorts of silly reasons for things that are perfectly explicable by other means.
Oxford Guy - Thursday, December 10, 2020 - link
Speculativeshelbystripes - Thursday, December 10, 2020 - link
It's ironic that you respond to someone calling out your unsubstantiated speculation as "speculative". If you're opposed to speculation, you should retract your statements assuming that manufacturers are out to "kneecap" MLC/TLC like they have some secret agenda against higher-reliability parts...Spunjji - Monday, December 7, 2020 - link
Do you have any evidence that would support that claim? Say, TLC costs rising even as QLC rolls out, in a way that doesn't reflect the usual industry supply/demand fluctations?Oxford Guy - Thursday, December 10, 2020 - link
Yes. The die sizes offered with TLC are 50% smaller at best. That magnifies the 30% density increase of QLC automatically. Maybe this reply will stick. Here’s to hoping.